1. Field of the Invention
This invention relates to gas insulated switch-gear in a pumping-up power station, and, more particularly, to an apparatus for phase switching between the pumping-up and generating operations in a pumping-up power station.
2. Description of the Prior Art
The recently developed hydraulic power station is being gradually replaced by the pumping-up power station because of operation efficiency. The housing therefor is a tunnel structure of underground structure which does not impair the adjacent environment. As a result, a switch gear employing sealed sulphur hexa-fluoride (SF.sub.6) has more restrictive sizing requirements.
On the other hand, the pumping-up power station needs apparatus for phase switching in order to permit the generator to function as a motor.
It is known that reversing the rotation of a three-phase motor is effected by reversing the connection of two of the three terminals. Accordingly, changing the generator from generator to motor is effected by reversing two switches. Two disconnecting switches, i.e. DS.sub.1 of the generator and DS.sub.2 of the motor, have been employed and phase-switched by alternative operation.
FIG. 1 shows a connecting diagram of the pumping-up power station. In FIG. 1, the generator G works as a pumping motor as described above. Tr designates a transformer, DS a main disconnecting switch, GCB a gas circuit breaker, DS.sub.1 and DS.sub.2 disconnecting switches for phase switching as described above, and BUS a bus bar.
A load (not shown) is connected to the bus bar BUS through a disconnecting switch DSa, a circuit breaker CB and a disconnecting switch DSb.
In such a structure, the disconnecting switch DS.sub.2 of the motor side as described above is necessary to phase-switch the generator from a generating operation to a motoring operation and to then connect the bus bar to another power line to operate the generator G as a motor. If the disconnecting switches DS.sub.1 and DS.sub.2 are closed together, a shorting fault occurs.
Accordingly, the disconnecting switches DS.sub.1 and DS.sub.2 must satisfy the following conditions. When the disconnecting switch DS.sub.1 of the generator side is closed, the disconnecting switch DS.sub.2 of the motor side must be open and vice versa, and the disconnecting switches DS.sub.1 and DS.sub.2 can be opened together.
In order to satisfy such conditions, an interlocking mechanism as shown in FIG. 2 is provided between the disconnecting switches DS.sub.1 and DS.sub.2.
A link LK with a clearance is provided between an actuating lever L.sub.1 of the disconnecting switch DS.sub.1 and an actuating lever L.sub.2 of the disconnecting switch DS.sub.2.
One end barring the clearance of the link LK is engaged with the lever L.sub.1 of the disconnecting switch DS.sub.1. Thus, the interlock mechanism IM comprises the link LK. In FIG. 2, like reference characters designate identical or corresponding parts as shown in FIG. 1.
However, since there is an interlocking mechanism, the structure of the arrangement and its adjustment are complicated. Further, since there are two disconnecting switches DS.sub.1 and DS.sub.2 separated from each other, the arrangement in general requires a great deal of space.